Hospital for Children and Adolescents, University of Helsinki, Helsinki, Finland
Received 11 June, 2006
Accepted 20 October, 2006
Address correspondence and reprint requests to Mikko Pakarinen, MD, PhD, Hospital for Children and Adolescents, University of Helsinki, Stenbäckinkatu 11, PO Box 281, Helsinki 00029-HUS, Finland (e-mail: firstname.lastname@example.org).
Background: Functional outcomes after treatment of low anorectal anomalies remain controversial. To address this, we conducted a controlled, prospective single-center long-term follow-up study of functional outcome in boys treated for perineal fistula with anoplasty.
Patients and Methods: Twenty-four consecutive boys treated exclusively for perineal fistula from 1992 to 2001 underwent prospective follow-up after completion of toilet training. All of the patients had identical surgical treatment. Functional outcome was assessed according to a previously validated bowel function score (7 questions, maximum score of 20). Daytime and nighttime wetting, as well as the age at toilet training, were also recorded. Thirty-seven age-matched boys served as healthy controls. An independent nurse specialist interviewed caregivers.
Results: Age of the patients (9.1 ± 2.6 years) and controls (9.0 ± 2.9 years) were similar. Seven patients (32%) had bowel function scores below the 10th percentile (17.2) of the controls, which was chosen as a lower limit of normality. The overall mean bowel function score was significantly lower (P < 0.01) among the patients (17.9 ± 1.9) compared with the controls (19.1 ± 1.2). The difference was attributed mainly to significantly lower scores (0–3) among patients in questions assessing constipation (2.4 ± 0.8 vs 2.9 ± 0.3; P < 0.05) and soiling (2.5 ± 0.5 vs 2.8 ± 0.4; P = 0.05). Constipation and soiling were significantly more common (P < 0.05) among patients (41% and 55%, respectively) compared with controls (8% and 24%, respectively).
Conclusions: Overall long-term bowel function is impaired in one third of boys with perineal fistula. The main reasons for impaired functional outcome are constipation and soiling, which affect as many as half the patients.
Functional outcomes in cases of low anorectal anomalies remain controversial. Earlier studies have suggested good or near-normal functional outcomes in patients with operatively treated low anorectal malformations (1,2). In contrast, more recent controlled studies have clearly indicated impaired anorectal function in a significant proportion of these patients (3–6). However, most previous studies have pooled several different types of low anorectal malformations treated with a variety of procedures in both sexes, which has hampered interpretation of functional results (3–6). In an attempt to avoid confounding effects of variable type of anorectal malformation, mode of treatment, and sex, we conducted a controlled, prospective single-center long-term follow-up of functional outcome in which only boys treated for perineal fistula with anoplasty were included. Functional outcome of perineal fistula should represent the best possible outcome after surgical correction of an anorectal malformation because perineal fistula may be considered the least severe form of anorectal malformation.
PATIENTS AND METHODS
All boys consecutively treated with anoplasty for perineal fistula from 1992 to 2001 at the Hospital for Children and Adolescents of the University of Helsinki, Finland, underwent prospective follow-up after completion of toilet training. Regular outpatient clinic follow-up of these patients is continued until early adulthood. The basic patient data were retrospectively collected from the hospital records using a standardized data extraction sheet. The type of anorectal malformation, surgical management, associated anomalies, complications, and outcome were recorded. In every boy included the type of anorectal malformation was perineal (ie, anocutaneous) fistula and the mode of surgical treatment was anoplasty, also known as the cutback procedure.
An identical surgical technique for anoplasty was employed in every case. Operations were performed by the 2 senior authors or by younger surgeons trained by them. Anoplasty was started by defining the external sphincter with electrostimulation. The anocutaneous fistula was laid open in the midline down to the middle of the external sphincter. After gentle dilation of the anus to the appropriate size, rectal mucosa was stitched to the perianal skin. The anal dilation program was started 2 weeks after the operation, and daily dilations were continued until the age-appropriate anal size was reached.
Functional outcome was prospectively assessed with a previously validated bowel function score (4). Individual factors and scores are shown in Table 1. Urinary continence was evaluated with questions assessing daytime and nighttime wetting (Table 2). The age at toilet training (separate ages for urine and feces) was also recorded. An independent nurse specialist interviewed caregivers. Thirty-seven age-matched healthy boys served as normal controls.
The data are presented as medians and ranges or as mean ± SD. When appropriate, the Mann-Whitney U test and χ2 test were used for comparisons between the groups. A simple regression analysis was used to examine associations between variables. P < 0.05 was considered statistically significant.
Only 1 patient was lost to follow-up. Another patient died of cardiac anomaly at the age of 1 month. The remaining 22 patients were included. Ten patients had associated anomalies and 2 had neurodevelopmental delay. Patient characteristics are summarized in Table 3.
All of the patients were operatively treated during the newborn period except 1 with delayed diagnosis at the age of 13 months. As a result of initial uncertainty of the level of anomaly, a covering sigmoidostomy was performed in 1 case. One patient underwent repeat anoplasty as a result of an incomplete primary procedure. Operative characteristics are shown in Table 4.
Age of the patients (9.1 ± 2.6 years) and the controls (9.0 ± 2.9 years) were similar. Seven patients (32%) had bowel function scores below the 10th percentile (17.2) of the controls, which was chosen as a lower limit of normal. Comparison of the percentage distribution of bowel function scores showed that scores >18 were markedly more frequent among controls in relation to patients with perineal fistula. Conversely, 14% of the patients with perineal fistula had scores of 14, whereas the lowest score among controls was 16 (6%). The percentage distribution of bowel function scores in both groups is shown in Figure 1.
Detailed functional outcome is shown in Tables 5 and 6. The mean bowel function score was significantly lower (P < 0.01) among the patients compared with the controls. The difference was attributed to significantly lower scores among patients in questions assessing constipation (P < 0.05) and soiling (P = 0.05). Constipation scores (r = 0.71; P < 0.001) and soiling scores (r = 0.62; P < 0.01) showed close positive association with the overall bowel function score among the patients. The percentage of patients with any degree of soiling (55%) or constipation (41%) was also significantly higher (P < 0.05) compared with controls (24% and 8%, respectively). Twenty-seven percent of the patients and 8% of the controls reported some degree of social problems related to bowel function, which restricted the social life of 1 patient. The difference between groups was not statistically significant.
Urinary continence scores (data not shown) and the mean age at toilet training were similar between the patients and controls (Table 5). Occasional (<1/week) daytime or nighttime wetting occurred in 3 patients.
In this controlled survey we examined functional long-term outcome in boys treated for perineal fistula with anoplasty. We examined all consecutive boys with perineal fistula between 1992 and 2001, and included only boys with perineal fistula to ascertain homogeneity of the study group. Moreover, caregivers of the patients and the controls were interview by an independent nurse specialist who had not been involved with surgical management of the patients. Comparison to a sex- and age-matched control group showed that as many as one third of boys with perineal fistula have impaired anorectal function, which was mainly attributed to constipation and soiling.
Perineal fistula may be viewed as the least severe form of anorectal malformation. Accordingly, functional outcome associated with perineal fistula should represent the best possible outcome after surgical correction of an anorectal malformation. In this light the results of the present study are not fully satisfactory, but they are in line with the findings of a previous controlled follow-up study including several types of low anorectal malformations in both sexes (3,4). The overall degree of functional impairment found in the present study may be classified as mild in terms of mean or median numeric scores, although individualized assessment gives a somewhat different picture. For example, 5 patients (23%) required laxatives for constipation, 12 patients (55%) had occasional soiling, and 5 patients (23%) had occasional fecal accidents. However, statistically significant differences in relation to the control group were observed only for constipation and soiling, underlining the importance of an adequate control group.
Constipation is a common finding after surgical repair of low anorectal malformations, occurring in approximately 50% of patients (4,5,7). The reason for constipation remains unclear, and it seems to occur similarly regardless of surgical technique used (4,5,7). Our finding of a 42% constipation rate is in accordance with the findings of previous reports (4,7). Occurrence of constipation following anoplasty requiring limited surgical dissection suggests that constipation is mainly caused by the anomaly itself rather than by the operation.
Previous studies have reported soiling frequencies between 9% and 12% in patients with low anorectal malformations (4,6,7). In the present study the frequency of soiling among boys with perineal fistula was clearly higher (55%). We defined soiling as fecal staining of underwear. In all cases soiling occurred less than once per week and did not require treatment in any case. Soiling was also relatively common among the controls (24%). Nevertheless, the difference is statistically and clinically significant. In our study the caregivers were interviewed by an independent nurse specialist instead of surgeons or nurses directly involved with patient care. We believe that more reliable and honest information is received when interviews are accomplished by an independent third party.
In cases of perineal fistula, the anus, although anteriorly displaced, is surrounded by the sphincter muscles. One may accept the anterior displacement of the anus and perform a simple anoplasty as in the present series, or perform more invasive posterior sagittal anorectoplasty in which the rectum is mobilized and brought into the middle of the sphincter complex, followed by reconstruction of the anal sphincters (8). It may be argued that the latter surgical approach is associated with better functional outcome. We have recently completed a comparison of functional outcomes between these 2 surgical techniques. Preliminary results suggest that functional outcome is similar after both procedures (9). In addition, the rates of constipation, soiling, and totally continent patients are comparable in case series of perineal fistula managed with posterior sagittal anorectoplasty and in follow-up studies after anoplasty (4,7).
In conclusion, overall long-term bowel function is impaired in one third of boys with perineal fistula treated with anoplasty. The main reasons for impaired anorectal function are constipation and soiling, which affect as many as half the patients. In most patients the nature of constipation and soiling is modest enough not to produce social problems or restrict social activities. Patients with operatively treated low anorectal malformations require continuing follow-up and care beyond childhood.
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